Nowadays, the application of the RFID technology is already relatively mature. Within a finite spatial range of effectively reading and writing, reading multiple RFID tags reliably at the same time isn't a technical bottleneck. However, due to the nature of the RFID technology, no reliable technologies are available to accurately derive the spatial sequence of multiple RFID tags within a three-dimensional space currently. In other words, prior arts can recognize the presence and the identities of multiple RFID tags and then read and write the tags, but can't derive the relative spatial relationships between and among these RFID tags or between the signal source and the RFID tags.